In conjunction with the advance of the IT (Information Technology), there are increasing opportunities for receiving desired services by using a portable telephone or portable information terminal carrying a credit card number, and an IC card carrying a PKI secret key, etc. For example, there are many existing services in which a user can log-in by using a password of the user and view information, or purchase goods by using a credit card number of the user.
In such cases, if the user loses the portable telephone or portable information terminal and the IC card which store the above described secret information (such as a password, a credit card number, a PKI secret key, etc.), there is a need to have that secret information invalidated and a new secret information re-issued by reporting the loss to the issuer.
However, when the user loses the own secret information, there is a problem that the lost secret information must be invalidated while changing the secret information, for the purpose of maintaining the security. There is also a problem that the user cannot receive services until the secret information is re-issued because the secret information is to be changed.